I think in the json-lsd work this is being called type coercion but the desired coersions are taken not from the schema but from a serialised document preamble. A lot of rdf processing takes place without actually considering the schema or even having a copy of it - perhaps this was the problem first time around?
Dan Brickley <danbri@danbri.org> a écrit :
>Hi folks
>
>Firstly, apologies I couldn't make today's call. I've spent my RDF'ing
>time this week talking to a lot of people about schema.org,
>rdfa/microdata etc.
>
>I want to bring something up related to that: back in RDFCore WG we
>called it "long range" data-typing, but didn't figure out a way to
>make it work. I'd appreciate if someone could articulate the
>connection to current discussion on literals, and suggest if there are
>ways we could make it work in 2011.
>
>The idea is that many properties are deployed as if their values take
>string form, but we know from the schema that the values can be
>interpreted e.g. as integers or dates.
>
>RDF's datatyping mechanism puts a lot of burden on instance data, and
>in some contexts (eg. Website markup) this can be problematic. So for
>example http://schema.org/docs/datamodel.html chooses Microdata over
>RDFa and lists 'datatypes' as one of the complexity burdens of RDFa
>markup.
>
>In practice I don't think a lot of sites will enjoy marking up each
>property value occurence with a datatype, ... and so vocabulary
>designers are tending not to make datatyping explicit.
>
>So for example in FOAF we have foaf:age, which Peter Mika originally asked for.
>
>http://xmlns.com/foaf/0.1/#term_age "The age property is a
>relationship between a Agent and an integer string representing their
>age in years. "
>
>This can be used in RDFa as so: <p>blah blah <span
>property="foaf:age">39</span> blah</p>.
>
>If we try to persuade publishers to put datatype="xsd:integer"
>alongside each age, ... we'll have a hard time. So is there anything
>we can do at the schema level? Mumble mumble range mumble...
>
>Pat - can you remember why we couldn't make this work in the semantics
>last time?
>
>cheers,
>
>Dan
>
>(another possibility is to do something in RDFa's profile mechanism,
>http://www.w3.org/TR/rdfa-core/#s_profiles )
>